Various Fix

 - Fix: master/buildbot/buildslave/manager.py
   - __repr__ method of BuildslaveRegistration
 - Fix: master/buildbot/process/buildrequest.py
   - set ss.patch to None instead of (None, None, None)
 - Fix: master/buildbot/status/buildstep.py
   - Make BuildStepStatus picklable
 - New BuildRequest are processed:
   - Change the filter of BotMaster::buildrequest_consumer_new from ('buildrequest', None, None, None, 'new')
   to ('buildset', None, 'builder', None, 'buildrequest', None, 'new'), otherwise the BuildRequestDistributor activity_loop is never wakeup
   on a new buildRequest.
   - Note: This is certainly a temporary fix.